Here's a strange question: I've seen presentations on the web that talk about RBEs being a specialized combination of MPCs between nodes.
Does anyone know of a reference that actually shows the MPC formulation for an RBE2? how about an RBE3?
The NX NASTRAN R-type elements are elements that imposes fixed constraints between components of motion at the grid points or scalar points to which they are connected. Thus, an R-type element is mathematically equivalent to one or more multipoint constraint equations. Each constraint equation expresses one dependent degree of freedom as a linear function of the independent degrees of freedom.
Although sometimes the R-type elements are referred to collectively as rigid elements, the name “rigid” is misleading. The R-type elements that are rigid consist of the RROD, RBAR, RBE1, RBE2, and RTRPLT. The RBE3 and RSPLINE are interpolation elements and aren’t rigid. The RBE2 and RBE3 elements are the most commonly used R-type elements in the NX Nastran element library.
To learn more about RBE2 vs. RBE3 you can visit my blog in the following address:
Try this link:
If the link doesn't work, just Google "rbe3 formulation"
It covers RBE3 formulation pretty well.